The invention relates to sewing machines, and specifically to sewing machines that perform a lap seam stitch.
A lap seam is generally sewn on a feed-off-the-arm sewing machine, and is used to join two plies of material that are positioned on top of one another. In one method, the plies are presented to the machine with the ends turned up. The machine trims the ends, folds the trimmed ends down on top of one another and sews the lap seam stitch. The terms "sewing on" and "sewing off" refers to the practice of starting the stitch forming process before feeding the material to be stitched to the needle area and then continuing the stitch forming process after the material being stitched has exited the needle area. When "sewing on" and "sewing off" with a standard 607 stitch a ribbon is formed prior to where sewing began and again where sewing ceased. These ribbons of stitching are trimmed off the finished product.
The lap seam stitch is used on many knitted garments, such as men's briefs, sweatshirt and sweatpants. These garments have a thick binding at each end that generally runs perpendicular to the direction of the lap seam and frequently contains an elastic material.
When sewing on or off the machine with these types of garments a peak in the binding may develop. When peaking occurs, the binding of the left ply does not align, along a straight line, with -the binding of the right ply. Instead, either a gap or an angle in the binding is observed. Peaking causes the material to be susceptible to tearing, is unsightly, and is uncomfortable to the wearer. Accordingly, peaking in the lap seaming stitch is not acceptable.
One attempt at solving the peaking problem has been to lay the left ply down flat and trim the right ply only. But this procedure reveals the raw edge of the untrimmed left ply because it is not sewn inside the width of the stitch.
This invention solves the peaking problem and provides for trimming of both the left and the right ply. Thus, when sewing a lap seam stitch on two plies with bindings, the binding is align with one another when sewing on and off the garment. In addition, because both the left and the right ply are trimmed, a clean seam showing no raw edge is produced.